This invention generally relates to an apparatus for reprocessing old paper in a series of flotation cells arranged one behind another, in which the suspension discharge from the front cell is connected to the suspension inlet of the following flotation cell and each flotation cell is provided with a stirring member, an air inlet device and a foam discharge opening.
A flotation cell of this kind is, for example, disclosed in German Patent DE-AS No. 15 17 227. A disadvantage of such flotation cells is that the cells are in general open at the top and at least one open foam outlet is present. For this reason, damage to the environment may occur, the amount being dependent on the size and area of the container, the nature and state of the old paper to be treated. For this reason costly covers and/or costly room ventilation and room air discharge apparatus must be provided. Both expedients are very expensive. In addition, a flotation apparatus of this kind occupies considerable space, because in order to achieve suitable whiteness a relatively large number of cells arranged one behind the other is necessary.